The present invention generally relates to a dental imager and related method for collecting digital impressions. More specifically, the present invention relates to a dental imager in the form of a hand-manipulatable scanner that digitally records three-dimensional images of the contours and surfaces of the oral cavity when biased away and passed over teeth.
A dental impression is a reproduction of an oral cavity. Dentists, orthodontists, and dental practitioners collect dental impressions for a variety of reasons, such as making removable dentures, making and installing dental crowns, creating a dental bridge, repairing installed dentures, making a mouth guard or customized enamel whitening tray, creating models for diagnostic study, or manufacturing and installing other oral appliances, etc.
Currently, trained practitioners can take dental impressions by creating a solid mold of the oral cavity. The process requires filling a “U” shaped plastic tray with a hardening chemical paste that is then pushed up and around the entire dental arc of the patient. The paste hardens into an impression body, creating a negative relief of the mouth of the patient. A durable mold can then be created using the negative space of the impression body. This form of recording dental impressions presents numerous limitations and inconveniences.
For example, the chemical paste used to create the impression must solidify when applied to the dental arc of a patient. The solidification process may be an uncomfortable experience for patients who remain in a reclined position with their mouth open for a prolonged period of time (e.g., six to ten minutes). Moreover, the chemical paste generates excessive salivation during the impression curing process, which can limit the ability of the patient to breathe properly, especially when reclined. The removal of the cured dental impression can also be an uncomfortable experience for the patient, even when done properly. Discomfort is compounded by the fact that chemical pastes used to create the dental impression may leave a bad taste in the mouth, even after removal, as residues of the paste get stuck in the cracks of the teeth.
Moreover, the physical impression is typically unable to capture every indentation, crack, or protuberance of the oral cavity. For example, if the patient has attachments on the surface of their teeth, including braces or permanent retainers, the entire process is compromised and it may not be possible to create a physical dental impression. This is because the attachments unavoidably jeopardize the accuracy and integrity of the impression during the curing and removal steps. Moreover, the inability to prevent scratching of the cured chemical paste mold sometimes results in the undesirable need to re-take the dental impressions (i.e., re-do the mold).
The nature, consistency, and malleability of physical dental impression bodies also make taking a targeted impression of only a limited area within the oral cavity extremely difficult, if not impossible. Thus, skilled practitioners typically make an impression of the entire dental arc, even if the patient only requires treatment on a single tooth or area of the oral cavity. Creating dental impressions with an impression and mold also creates excessive waste from both the impression curing process and the creation of the durable resulting mold. Of course, this also means that practitioners must continually purchase the consumables needed to make the impressions and molds.
Creating physical dental impressions may also be time consuming and labor intensive. For example, after the “U”-shaped plastic tray with the chemical paste is pushed up and around the entire dental arc of the patient, the practitioner must wait for the chemical paste to cure. Thereafter, the practitioner must wait upwards of several hours for the dental stone material poured into the casting formed by the cured chemical paste to cure or solidify. Personnel must also be highly trained to take physical dental impressions using the current impression body and mold method, as it is easy to improperly: (a) mix the chemical paste; (b) apply the chemical paste to the “U”-shaped tray; (c) insert the tray into the mouth; (d) wait an insufficient duration for the dental impression to cure; (e) remove the tray once the impression cures; or (f) create a mold from the cured dental impression. Inadequately trained and especially inexperienced personnel inevitably need to take multiple dental impressions of the same patient in one sitting, until a proper mold has been generated. This is undesirable for the patient and practitioner.
Over the course of the last thirteen years, several technologies have been produced to try and introduce a better way of taking dental impressions, such as by scanning the dental arc and creating a 3D digital model. Some systems disclosed in the prior art incorporate light-based scanning systems to create a three-dimensional digital representation of the oral cavity. In this respect, some systems are designed to mimic the “U”-shape dental trays in the form of a scanner, but those too include limitations regarding the wide scanning area and the amount of data gathered. For example, instead of targeting just the teeth, these scanners record significant portions of the gums, and some portions of the upper roof and lower bottom of the mouth. As a result, the 3D scanned digital impressions must be subject to a higher amount of digital work and adjustment via computer software, to be ready for 3D or casting of the mold by the dentist. Moreover, the “U”-shaped dental scanners are also unable to efficiently take an impression of a single tooth or selected area of the mouth given that the “U”-shaped tray necessitates scanning the entire dental arc, thereby inherently including the same limitations as current methods related to “U”-shaped trays that utilize chemical paste. While these systems may be designed to replace curing chemical pastes with digital scanners, such systems are not necessarily significantly more efficient.
For example, U.S. Publication No. 2012/0064477 to Schmitt, the contents of which are herein incorporated by reference in their entirety, discloses a dental impression tray that includes a deformable impression compound therein for obtaining a dental impression. One or more sensors may be positioned to identify changes in the deformable impression compound when taking an impression of the oral cavity. The sensors may identify different arrangements, shapes, and/or dimensions and relay such information to a processor to create a digital representation of the oral cavity. In this example, the deformable impression compound is disposed within the interior of a “U”-shaped tray and closely resembles the chemical-curing trays traditionally used for creating dental impression molds.
In another example, U.S. Pat. No. 6,976,841 to Osterwalder, the contents of which are herein incorporated by reference in their entirety, discloses an intra-oral dental irradiation imager that uses a number of scanners arranged in a “U”-shaped tray to harden material therein, similar to the chemical trays used for generating whole dental-arc impression bodies. In making dental impressions, the device projects light in a spectrum that functions as a catalyst to harden material within the “U”-shaped tray, similar to the traditional process of creating physically-cured dental impression molds. The scanners are arranged throughout the “U”-shaped tray to harden the dental impression material when inserted over the teeth of the patient.
U.S. Pat. No. 6,386,867 to Durbin, the contents of which are herein incorporated by reference in their entirety, discloses a “U”-shaped mouthpiece with a camera permanently attached to a fixed “U”-shaped track. The camera slides to a plurality of predetermined positions along the fixed curved track to capture images of the dental structure within the oral cavity. An air-directing nozzle is movably coupled with the camera along the “U”-shaped track to ensure that the tooth-gum interface is free from unwanted debris during imaging.
U.S. Publication No. 2005/0202363 also to Osterwalder, the contents of which are herein incorporated by reference in their entirety, discloses a “U”-shaped dental tray similar in structure to chemical trays used for making traditional physical dental impression molds, but with a plurality of LED lights fixed on an interior surface thereof, and a plurality of imaging sensors fixed on an opposite interior surface thereof. The LED lights and the imagining sensors are not moveable. In this respect, light emitted from the LEDs is refracted by the teeth situated between the LEDs and the sensors. The sensors capture and record an image of the teeth based on the light passing therethrough. Although, illumination and recordation of translucent oral objects does not allow for readily-available surface mapping, as the light passes through the object before being recorded, rather than bouncing off the object. Consequently, it is not possible to image completely opaque objects.
U.S. Publication No. 2015/0079534 to Tsuji, the contents of which are herein incorporated by reference in their entirety, discloses a “U”-shaped tray containing patterned light projectors and imaging sensors. The tray is used to take three-dimensional intraoral images of teeth by activating the light projectors within the interior surface of the “U”-shaped tray and recording the intersection of the light patterns using the installed sensors. The sensors and projectors are set in fixed positions within the tray.
In other known digital impression systems, light-based scanners are implemented as part of a hand-held tool that can be freely maneuvered around the oral cavity to collect digital impressions. For example, U.S. Pat. No. 8,520,925 to Duret, the contents of which are herein incorporated by reference in their entirety, discloses a hand-held sensor wand for taking three-dimensional color imprints of surfaces. The sensor wand houses a set of at least two CCD or CMOS color sensors, in fixed positions in the wand base, and can be positioned over an area to collect a digital image. Although, without proper guides, it is difficult to achieve the correct shape and distances being scanned. Moreover, such a wand increases the potential for accidental scans of the tongue and other parts of the mouth, thereby decreasing the accuracy of the scans and/or requiring user training to ensure an accurate the 3D model is produced.
Despite addressing some of the problems associated with physical dental impression molds, known digital impression systems include drawbacks. For example, “U”-shaped scanner arrays and “U”-shaped tracks with movable scanners are limited by size and are not always able to fit every oral cavity size. This can present an issue, for example, when trying to scan the mouth of a child when using a device sized to scan an adult mouth. Practitioners would need to purchase a variety of differently-sized devices to cater to all patients. This means a large initial expense for equipment, thus inhibiting the potential cost advantage of foregoing the consumables needed to create physical dental impression bodies and molds.
The unconstrained nature of current hand-held scanning systems may require additional training so the practitioner understands how to obtain accurate images since a guide is notably absent. Furthermore, the practitioner must have a steady hand to ensure the accuracy of the images, depending on what is being imaged. For example, the practitioner must ensure that proper focal distances are maintained while scanning, and that the imaging sensor does not touch the surface being examined. These limitations can result in digital representations of the oral cavity that need correction or post-processing before being usable, thereby increasing time and cost for producing a dental impression.
There exists, therefore, a significant need in the art for a low cost adaptable dental imager that can record detailed three-dimensional representations of oral cavity surfaces, without needing cumbersome trays, expensive consumable products, or a trained and skilled user. The present invention fulfills these needs and provides further related advantages.